OK, prolly a simple question but since i know about zero about these rigs, I'll leave it to the pro's here. Normally, when i start my truck when its cold out here in CT, i can see the voltage meter rise and fall as the grid heater cycles on and off. so i'm used to seeing it over on the left side of the meter. Well, the other day, I noticed my check engine light was one and the voltage meter was sitting in the left edge of the "safe" zone on the meter. so, i checked the engine oil to make sure that wasn't the reason for the idiot light but the oil was fine. wasn't sure if the light and the volt meter corresponded to each other. well, today, driving home, the voltage meter basically bottomed out and i pretty much lost all the dash lights and headlights seemingly indicating that they were running off the batteries cuz they weren't getting charged. so is it the alternator? and if so, how hard is it to swap out myself? I have ok mechanical skill meaning i can usually get things done myself but it just takes a while sometimes. I have a battery charger sitting on it right now and the batteries are taking the charge.

thanks for your help guys!

DR

 

How old are your batteries? Have them checked, then pull your alternator off and have it checked. Most auto parts stores do this for free. Taking it off is fairly straight forward, or any shop can do it for you. Just be careful of the wires when you are working on it so you don't crimp them or "bruise" them, or break the connectors.

Yes, the check engine light comes on when the voltage gets too low.

 

thanks for the advice. much appreciated.

 

Check your crank sensor before you start chucking parts at the truck. If the PCM doesn't get a crank signal, it won't turn on the charging system. Also check the ASD relay. If those are OK, the problem is likely worn out brushes in the alternator. You can replace the brushes yourself for a lot less than a replacement alternator. http://www.fostertruck.com/ has the brushes.

 

If you have access to a voltage meter, it is real easy to check the alternator yourself. Disconnect the two small wires on the back of your alternator. Ground one terminal on the alternator and run 12v to the other with the truck running. Then check your voltage at battery. It should go to about 14v if it is charging. I just went through this with my truck. If you have a Denso alternator, the brushes are real easy to change. Mine also had a bad regulator which is built in the PCM. I bypassed mine with and old syle regulator for about 12 bucks. Charging great now!